Three-axis numerical control spindle head for automatic threading numerical control electric spark linear cutting machine tool

Abstract

A three-axis numerical control spindle head for an automatic threading numerical control wire cut electrical discharge machining tool is characterized in that the three-axis numerical control spindle head is provided with a Z-axis movement mechanism, a W1-axis movement mechanism and a W2-axis movement mechanism, and the Z-axis movement mechanism comprises a Z-axis carriage seat, a Z-axis carriage, a Z-axis guide rail pair, a wire guide pipe positioning mechanism and a Z-axis servo driving mechanism; the W1-axis movement mechanism comprises a W1-axis carriage, a W1-axis guide rail pair, a wire guide pipe, an electrode wire feeding mechanism and a W1-axis servo driving mechanism; the W2-axis movement mechanism comprises a W2-axis guide rail, a W2-axis first sliding block, a W2-axis second sliding block, a W2-axis first carriage, a W2-axis second carriage, a tension detector, a movable guide wheel, a fixed guide wheel and a W2-axis servo driving mechanism. According to the scheme, the electrode wire section which bypasses the movable guide wheel and moves downwards in the Z direction is the cutting working section of the electrode wire, the W2-axis movement mechanism controls the tension of the electrode wire and directly acts on the cutting working section of the electrode wire, and the tension control over the electrode wire of the cutting working section is more direct and accurate.

Description

Technical Field

[0001] The invention relates to the technical field of electric spark wire cutting processing, in particular to a three-axis numerical control spindle head for an automatic wire threading numerical control reciprocating wire electric spark wire cutting machine tool. Background Art

[0002] CNC reciprocating wire EDM machine (abbreviated as: EDM wire cutting machine) is a metal cutting processing equipment widely used in the processing of precision and complex parts in the manufacturing industries such as molds, aerospace, automobiles, energy, precision instruments, medical equipment, and electronic products, and plays an important role in industrial production. EDM wire cutting uses a continuously moving thin metal wire (called electrode wire) as an electrode to perform pulse spark discharge to erode metal and cut the workpiece into shape.

[0003] The mechanical system of the wire-cut EDM machine tool consists of a machine bed, a coordinate table, a wire transport mechanism, a wire rack mechanism, a taper mechanism, a lubrication system, etc. Among them, the wire transport mechanism refers to a mechanism used to drive the electrode wire to reciprocate, and the wire rack mechanism refers to a mechanism used to support the electrode wire. The wire rack mechanism is divided into a single-column cantilever type and a double-column gantry type. The single-column cantilever type is further divided into an upper wire arm and a lower wire arm. Generally, the lower wire arm is fixed, and the upper wire arm can be raised and moved (Z-axis motion). The "spindle head" in the CNC spindle head of this application refers to the upper wire arm that can be raised and moved (Z-axis motion), and "CNC" means that the lifting and moving (Z-axis motion) of the upper wire arm can be digitally controlled by a servo motor. Functionally, the CNC spindle head of the wire-cut EDM machine is used to install the upper wire guide nozzle, the upper working fluid nozzle and the upper guide wheel of the upper wire arm mechanism. This mechanism usually has a Z-axis motion mechanism, which can drive the upper wire guide nozzle, the upper working fluid nozzle and the upper guide wheel to perform CNC lifting and lowering movements along the Z-axis.

[0004] Wire threading is required before or during online cutting. Currently, most wire-cut EDM machines can only use manual wire threading. Manual wire threading is highly professional and requires professional personnel to operate. In addition, the process is complex, the requirements are high, the workload is large, and the efficiency is low. To this end, in recent years, technical personnel in this field have been working hard to research and develop fully automatic wire threading devices and methods suitable for wire-cut EDM machines. Fully automatic wire threading is a complex and detailed system engineering in the field of wire-cut EDM processing technology. It has high process requirements, many difficulties, and high technical difficulty. It has long been a technical problem in this field. Among them, how the spindle head of the wire-cut EDM machine can meet the control requirements of automatic wire threading for the movement of the relevant automatic wire threading mechanism in the Z-axis direction is one of the technical difficulties that need to be overcome.

[0005] The existing reciprocating wire EDM wire cutting machine is only equipped with a Z-axis, which can drive the upper wire guide mechanism to move in the Z-axis direction during the wire threading process, but cannot meet the machine tool's automatic wire threading control requirements for the movement of the relevant automatic wire threading mechanism in the Z-axis direction. In order to solve this technical problem, the present invention designs a three-axis CNC spindle head for an automatic wire threading reciprocating wire EDM wire cutting machine. Summary of the invention

[0006] The invention provides a three-axis CNC spindle head for an automatic wire threading CNC electric spark wire cutting machine tool, and aims to solve the problem that the existing spindle head motion mechanism cannot meet the control requirements of the machine tool automatic wire threading on the movement of the related automatic wire threading mechanism in the Z-axis direction.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a three-axis CNC spindle head for an automatic wire-threading CNC electric spark wire cutting machine tool, and its innovation lies in: the three-axis CNC spindle head has a Z-axis motion mechanism, a W1-axis motion mechanism and a W2-axis motion mechanism, and the up and down directions of the machine tool in the working state are defined as the Z direction, wherein the axes of the three axes, the Z axis, the W1 axis and the W2 axis, are all arranged parallel in the Z direction.

[0008] The Z-axis motion mechanism includes a Z-axis carriage seat, a Z-axis carriage, a Z-axis guide rail pair, a wire guide tube positioning mechanism and a Z-axis servo drive mechanism, wherein: The Z-axis carriage seat is fixed relative to the machine tool column, and the Z-axis carriage is connected to the Z-axis carriage seat through a Z-axis guide pair, and the Z-axis guide pair guides the Z-axis carriage to move precisely in the Z-axis direction.

[0009] The wire guide tube positioning mechanism is positioned and installed on the Z-axis carriage.

[0010] The Z-axis servo drive mechanism is positioned and installed on the Z-axis carriage seat. The Z-axis servo drive mechanism is connected to the Z-axis carriage driving and can drive the Z-axis carriage to perform digital linear motion in the Z direction.

[0011] The W1-axis motion mechanism includes a W1-axis carriage, a W1-axis guide rail pair, a wire guide tube, an electrode wire feeding mechanism, and a W1-axis servo drive mechanism, wherein: The W1-axis carriage is connected to the Z-axis carriage via a W1-axis guide pair, and the W1-axis guide pair guides the W1-axis carriage to perform precise movement in the W1-axis direction.

[0012] The electrode wire feeding mechanism is positioned and installed on the W1 axis carriage, and the wire guide tube is fixedly installed on the electrode wire feeding mechanism. In the assembled state, the axis of the wire guide tube is parallel to the Z direction. The electrode wire feeding mechanism is used to digitally feed the electrode wire into or out of the wire guide tube, and the wire guide tube positioning mechanism is used to position the lower part of the wire guide tube.

[0013] The W1-axis servo drive mechanism is positioned and installed on the Z-axis carriage. The W1-axis servo drive mechanism is connected to the W1-axis carriage driving and can drive the W1-axis carriage to perform digital linear motion in the Z direction between the designed strokes on the Z-axis carriage.

[0014] The W2-axis motion mechanism includes a W2-axis guide rail, a W2-axis first slider, a W2-axis second slider, a W2-axis first carriage, a W2-axis second carriage, a tension detector, a movable guide wheel, a fixed guide wheel, a movable guide wheel seat, a fixed guide wheel seat and a W2-axis servo drive mechanism, wherein: The W2-axis guide rail is fixedly mounted on the Z-axis carriage seat, the W2-axis first slider and the W2-axis second slider are both mounted on the W2-axis guide rail, and the W2-axis first slider and the W2-axis second slider are both able to make precise movements in the W2-axis direction along the W2-axis guide rail, and the W2-axis first slider is located above the W2-axis second slider.

[0015] The first carriage of the W2 axis is fixedly connected to the first slider of the W2 axis, and the second carriage of the W2 axis is fixedly connected to the second slider of the W2 axis.

[0016] The tension detector has an upper acting end and a lower acting end, the upper acting end is fixedly connected to the first drag plate of the W2 axis, and the lower acting end is fixedly connected to the second drag plate of the W2 axis. The connecting line between the upper acting end and the lower acting end is parallel to the Z direction, so that the force direction of the tension detector is the Z direction.

[0017] The movable guide wheel is rotatably connected to the movable guide wheel seat, and the movable guide wheel is positioned and connected to the second carriage of the W2 axis through the movable guide wheel seat. The axis of the movable guide wheel is perpendicular to the Z direction. The axis of the electrode wire that passes by the movable guide wheel and goes down in the Z direction is coaxial with the axis of the wire guide hole of the wire guide tube and is parallel to the Z direction. The fixed guide wheel is rotatably connected to the fixed guide wheel seat, and the fixed guide wheel is fixedly connected to the Z-axis carriage seat through the fixed guide wheel seat, and the axis of the fixed guide wheel is parallel to the axis of the movable guide wheel.

[0018] The W2-axis servo drive mechanism is positioned and installed on the Z-axis carriage seat. The W2-axis servo drive mechanism is connected to the driving force of the W2-axis first carriage, and can drive the W2-axis first carriage and drive the W2-axis second carriage to perform digital linear motion in the Z direction through the tension detector. The movement range of the W2-axis first carriage is between the highest position of the W1-axis carriage in the Z direction and the upper limit position of the W2-axis first carriage.

[0019] In the working state, the electrode wire section that bypasses the moving guide wheel, descends in the Z direction and passes through the wire guide hole of the wire guide tube to the wire guide nozzle on the lower wire arm of the machine tool is the cutting working section of the electrode wire.

[0020] In the working state, the gravity of the second slider of the W2 axis, the second carriage of the W2 axis, the moving guide wheel seat, the moving guide wheel and the electrode wire tension acting on the moving guide wheel act vertically downward along the Z direction on the lower acting end of the tension detector. The servo drive mechanism of the W2 axis acts vertically upward along the Z direction on the upper acting end of the tension detector through the pulling force of the first carriage of the W2 axis. The machine tool control system can achieve constant tension control of the electrode wire according to the electrode wire tension data measured by the tension detector by servo control of the W2 axis drive to drive the first carriage of the W2 axis and the moving guide wheel, and the electrode wire tension control directly acts on the cutting working section of the electrode wire.

[0021] The relevant contents in the above technical solution are explained as follows: 1. In the above scheme, the wire guide tube is a slender tubular structure, in the middle of which is an axially penetrating wire guide hole, which is used to guide automatic wire threading, and the axis of the wire guide hole is parallel to the Z direction. The slender tubular structure of the wire guide tube means that the wire guide tube is a tubular structure with a small diameter and a long length, with a diameter in the range of Φ1-Φ20mm, a length in the range of 100-1000mm, and an aspect ratio in the range of 5:1-500:1. Preferably, the diameter is in the range of Φ2-Φ8mm, the length is in the range of 100-1000mm, and the aspect ratio is in the range of 10:1-300:1.

[0022] The electrode wire feeding mechanism is located above the wire guide tube and is arranged directly opposite to the wire threading entrance of the wire guide tube.

[0023] The wire guide tube positioning mechanism is a positioning clamping structure for the lower part of the wire guide tube, and a positioning hole is provided on the positioning clamping structure. The positioning hole is used to position the outer cylindrical surface of the lower part of the wire guide tube, and the positioning center axis of the positioning hole for the outer cylindrical surface of the lower part of the wire guide tube is coaxial with the axis of the wire guide hole of the wire guide tube. The positioning clamping structure can automatically lock or release the lower part of the wire guide tube in the positioning hole under the control of the machine tool control system. In the released state, the W1-axis servo drive mechanism can drive the wire guide tube to move up and down along the axial direction in the positioning hole through the W1-axis drag plate.

[0024] 2. In the above scheme, the Z-axis guide pair is composed of a Z-axis guide rail and a Z-axis slider. One of the Z-axis guide rail and the Z-axis slider is fixedly mounted on the Z-axis carriage seat, and the other is fixedly mounted on the Z-axis carriage. The Z-axis guide rail is arranged along the Z-axis, and the Z-axis slider is mounted on the Z-axis guide rail and can make precise movements in the Z-axis direction.

[0025] 3. In the above scheme, the Z-axis guide pair consists of a Z-axis fixed rail and a Z-axis movable rail. The Z-axis fixed rail is fixedly connected to the Z-axis carriage seat, the Z-axis movable rail is fixedly connected to the Z-axis carriage, and the Z-axis fixed rail and the Z-axis movable rail are movably matched.

[0026] 4. In the above scheme, the Z-axis servo drive mechanism is composed of a synchronous pulley pair, a Z-axis screw nut pair and a Z-axis servo motor, wherein the synchronous pulley pair is composed of a small pulley, a large pulley and a synchronous belt, and the Z-axis screw nut pair is composed of a Z-axis screw and a Z-axis nut.

[0027] The Z-axis servo motor is fixedly mounted on the Z-axis carriage seat, and the Z-axis servo motor is connected to the small pulley in a transmission manner, and the axis of the Z-axis servo motor is coaxial with the axis of the small pulley and parallel to the Z direction. The small pulley is connected to the large pulley in a transmission manner through a synchronous belt, and the axis of the small pulley is parallel to the axis of the large pulley. The large pulley is connected to the Z-axis lead screw in a transmission manner, and the Z-axis lead screw cooperates with the Z-axis nut, and the axis of the large pulley, the axis of the Z-axis lead screw, and the axis of the Z-axis nut are coaxial and parallel to the Z direction. The Z-axis nut is fixedly connected to the Z-axis carriage.

[0028] 5. In the above scheme, the W1 axis guide pair is composed of a double cylindrical guide rod and a linear guide sleeve combination, wherein the double cylindrical guide rod and linear guide sleeve combination is composed of two cylindrical guide rods and four linear bearings.

[0029] Two bearing seats are set for the four linear bearings, two linear bearings are fixedly installed in parallel on one bearing seat, and the other two linear bearings are fixedly installed in parallel on the other bearing seat. The two bearing seats are arranged at a distance up and down in the Z direction and fixedly installed on the Z-axis slide. The axes of the four linear bearings on the two bearing seats are coaxial in pairs in the up and down directions, and are parallel in pairs in the left and right directions and parallel to the Z direction, thereby forming two groups of coaxial linear bearings.

[0030] A positioning connection block is set for the two cylindrical guide rods, and the two cylindrical guide rods are correspondingly inserted into the inner holes of the two sets of coaxial linear bearings. The upper ends of the two cylindrical guide rods are fixedly connected by the positioning connection block, and the center distance between the two cylindrical guide rods is maintained. The lower ends of the two cylindrical guide rods are positioned and fixedly connected to the W1-axis slide plate.

[0031] 5. In the above scheme, the W1-axis servo drive mechanism is composed of a W1-axis lead screw nut pair and a W1-axis servo motor, the W1-axis lead screw nut pair is composed of a W1-axis lead screw and a W1-axis nut, the W1-axis servo motor is fixedly mounted on the Z-axis carriage through a W1-axis motor seat, the motor shaft of the W1-axis servo motor is coaxially fixedly connected with the W1-axis lead screw, the motor shaft axis of the W1-axis servo motor is parallel to the Z direction, the W1-axis nut cooperates with the W1-axis lead screw, and the W1-axis nut is fixedly connected relative to the W1-axis carriage. In order to simplify the structure and reduce costs, the W1-axis lead screw nut pair and the W1-axis servo motor can use a servo motor with a lead screw nut pair.

[0032] 6. In the above scheme, the W2-axis servo drive mechanism is composed of a W2-axis screw nut pair and a W2-axis servo motor, the W2-axis screw nut pair is composed of a W2-axis screw and a W2-axis nut, the motor shaft of the W2-axis servo motor is coaxially fixedly connected with the W2-axis screw, the motor shaft axis of the W2-axis servo motor is parallel to the Z direction, the W2-axis nut cooperates with the W2-axis screw, and the W2-axis nut is fixedly connected to the first slide plate of the W2-axis.

[0033] Due to the application of the above scheme, the present invention has the following substantial characteristics and effects compared with the prior art: 1. The present invention ingeniously designs the W1-axis motion mechanism and the W2-axis motion mechanism on the Z-axis carriage and the Z-axis carriage seat, which has a compact structure, is scientific and reasonable, and meets the functional requirements of automatic wire threading of the machine tool; 2. The present invention can install the electrode wire feeding mechanism (wire feeding mechanism) and wire guide tube of the machine tool automatic wire threading system on the W1-axis carriage, and can drive the electrode wire feeding mechanism and the wire guide tube to perform digital linear motion along the Z direction under the drive of the W1-axis servo motor, thereby meeting the Z-direction motion control requirements of the electrode wire feeding mechanism and the wire guide tube during automatic wire threading.

[0034] 3. The W2-axis motion mechanism of the present invention realizes the online detection of the tension change of the machine tool electrode wire by the tension detector through the connection structure design of the tension detector. The machine tool control system can realize the constant tension control of the electrode wire through the servo control of the W2-axis servo motor according to the measured electrode wire tension data. In particular, the W2-axis motion mechanism directly acts on the cutting working section of the electrode wire to control the tension of the electrode wire, avoiding the existing tension control mechanism that does not directly act on the cutting working section of the electrode wire for tension detection and control, and the existence of links such as guide wheels and feed blocks between the tension control section of the electrode wire and the cutting working section, resulting in indirect tension control and additional deviations. Therefore, the design of the present invention is more direct and more accurate in controlling the tension of the electrode wire in the cutting working section.

[0035] 4. The W2-axis motion mechanism of the present invention can not only better control the tension of the electrode wire during machine tool cutting processing, but also can set different tension values ​​according to the requirements of automatic wire threading during the automatic wire threading process, control the tension of the electrode wire, and cooperate with the machine tool wire storage drum and wire feeding mechanism to complete the automatic wire collection task of the electrode wire.

[0036] 5. The Z-axis slide of the present invention can drive the wire guide tube positioning mechanism installed at its lower end to make digital linear motion in the Z direction, and can also drive the W1 axis to move synchronously in the Z direction, which not only meets the normal cutting requirements of the machine tool, but also meets the automatic wire threading requirements of the machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Attached Figure 1 This is a front view of a three-axis CNC spindle head according to an embodiment of the present invention.

[0038] Attached Figure 2 for Figure 1 A partial enlarged view of .

[0039] Attached Figure 3 This is a top view of the three-axis CNC spindle head according to an embodiment of the present invention.

[0040] Attached Figure 4 It is a right view of the three-axis CNC spindle head according to an embodiment of the present invention.

[0041] Attached Figure 5 for Figure 4 A partial enlarged view of .

[0042] Attached Figure 6 for Figure 4 AA section view.

[0043] Attached Figure 7 for Figure 6 A partial enlarged view of .

[0044] Attached Figure 8 It is the principle diagram of the W2-axis motion mechanism of the present invention.

[0045] In the above figures: 1. Z-axis carriage seat; 2. Z-axis carriage; 3. Z-axis servo motor; 4. W1-axis carriage; 5. W1-axis servo motor; 6. W2-axis guide rail; 7. W2-axis first slider; 8. W2-axis second slider; 9. W2-axis first carriage; 10. W2-axis second carriage; 11. Tension detector; 12. Moving guide wheel; 13. Fixed guide wheel; 14. Moving guide wheel seat; 15. Fixed guide wheel seat; 16. W2-axis servo motor; 17. Upper action end; 18. Lower action end; 19. .Wire guide tube; 20. Electrode wire feeding mechanism; 21. Electrode wire; 22. Z-axis guide rail; 23. Z-axis slider; 24. Small pulley; 25. Large pulley; 26. Synchronous belt; 27. Z-axis screw; 28. Z-axis nut; 29. ​​Cylindrical guide rod; 30. Linear bearing; 31. Bearing seat; 32. Positioning connecting block; 33. W1-axis screw; 34. W1-axis nut; 35. W1-axis motor seat; 36. W2-axis screw; 37. W2-axis nut; 38. Wire guide tube positioning mechanism. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Embodiment: A three-axis CNC spindle head for an automatic wire threading CNC electric spark wire cutting machine tool.

[0047] like Figure 1-8 As shown, the three-axis CNC spindle head has a Z-axis motion mechanism, a W1-axis motion mechanism and a W2-axis motion mechanism. The up and down direction of the machine tool in the working state is defined as the Z direction, wherein the axes of the three axes, the Z axis, the W1 axis and the W2 axis, are all arranged parallel in the Z direction.

[0048] The Z-axis motion mechanism includes a Z-axis carriage seat 1 (see Figure 2 and Figure 7 )、Z-axis carriage 2 (see Figure 5 and Figure 7 )、Z-axis guide rail pair, wire guide tube positioning mechanism 38 (see Figure 2 , Figure 5 and Figure 7 ) and a Z-axis servo drive mechanism, wherein: The Z-axis carriage seat 1 is fixed relative to the machine tool column, and the Z-axis carriage 2 is connected to the Z-axis carriage seat 1 through a Z-axis guide pair, which guides the Z-axis carriage 2 to move precisely in the Z-axis direction. In this embodiment, the Z-axis guide pair is composed of a Z-axis guide rail 22 and a Z-axis slider 23 (see Figure 7 ), the Z-axis guide rail 22 is fixedly mounted on the Z-axis carriage seat 1, and two Z-axis sliders 23 are fixedly mounted on the Z-axis carriage 2 (see Figure 7 ). The present invention is not limited to this, and the Z-axis slider 23 can also be fixedly mounted on the Z-axis carriage seat 1, and the Z-axis guide rail 22 can be fixedly mounted on the Z-axis carriage 2. That is, one of the Z-axis guide rail 22 and the Z-axis slider 23 is fixedly mounted on the Z-axis carriage seat 1, and the other is fixedly mounted on the Z-axis carriage 2. The Z-axis guide rail 22 is arranged along the Z axis (see Figure 7 ), two Z-axis sliders 23 are installed on the Z-axis guide rail 22 (see Figure 7 ), and can make precise movement in the Z-axis direction. In short, the best solution is: the Z-axis guide rail pair consists of a Z-axis fixed rail and a Z-axis movable rail, the Z-axis fixed rail is fixedly connected to the Z-axis carriage seat 1, the Z-axis movable rail is fixedly connected to the Z-axis carriage 2, and the Z-axis fixed rail and the Z-axis movable rail move in coordination.

[0049] The Z-axis servo drive mechanism is positioned and installed on the Z-axis carriage seat 1. The Z-axis servo drive mechanism is connected to the Z-axis carriage 2 and can drive the Z-axis carriage 2 to perform digital linear motion in the Z direction. In this embodiment, the Z-axis servo drive mechanism is composed of a synchronous pulley pair, a Z-axis lead screw nut pair and a Z-axis servo motor 3, wherein the synchronous pulley pair is composed of a small pulley 24, a large pulley 25 and a synchronous belt 26 (see Figure 2 and Figure 3 ), the Z-axis screw nut pair consists of a Z-axis screw 27 and a Z-axis nut 28 (see Figure 7 ).

[0050] The Z-axis servo motor 3 is fixedly mounted on the Z-axis carriage seat 1 (see Figure 2 ), the Z-axis servo motor 3 is connected to the small pulley 24 in transmission, and the axis of the Z-axis servo motor 3 is coaxial with the axis of the small pulley 24 and parallel to the Z direction (see Figure 2 The small pulley 24 is connected to the large pulley 25 through a synchronous belt 26 (see Figure 3), the axis of the small pulley 24 is parallel to the axis of the large pulley 25 (see Figure 2 The large pulley 25 is connected to the Z-axis lead screw 27 (see Figure 7 ), the Z-axis screw 27 cooperates with the Z-axis nut 28 (see Figure 7 ), the axis of the large pulley 25, the axis of the Z-axis lead screw 27, and the axis of the Z-axis nut 28 are coaxial and parallel to the Z direction (see Figure 7 The Z-axis nut 28 is fixedly connected to the Z-axis carriage 2 (see Figure 7 ).

[0051] The W1 axis motion mechanism includes a W1 axis carriage 4 (see Figure 5 )、W1 axis guide rail pair, wire guide tube 19 (see Figure 1 and Figure 2 )、Electrode wire feeding mechanism 20 (see Figure 2 , Figure 3 and Figure 5 ) and W1 axis servo drive mechanism, where: The W1 axis carriage 4 is connected to the Z axis carriage 2 through the W1 axis guide rail pair, and the W1 axis guide rail pair guides the W1 axis carriage 4 to move precisely in the W1 axis direction. In this embodiment, the W1 axis guide rail pair is composed of a double cylindrical guide rod and a linear guide sleeve combination, wherein the double cylindrical guide rod and linear guide sleeve combination is composed of two cylindrical guide rods 29 and four linear bearings 30 (see Figure 5 ).

[0052] Two bearing seats 31 are provided for the four linear bearings 30 (see Figure 5 ), two linear bearings 30 are fixedly mounted in parallel on a bearing seat 31 (see Figure 5 ), the other two linear bearings 30 are fixedly mounted in parallel on another bearing seat 31 (see Figure 5 ), the two bearing seats 31 are arranged at a distance in the Z direction and fixedly mounted on the Z-axis carriage 2 (see Figure 5 ), the axes of the four linear bearings 30 on the two bearing seats 31 are coaxial in pairs in the vertical direction, and are arranged in pairs in the left and right direction and parallel to the Z direction, thereby forming two sets of coaxial linear bearings 30 (see Figure 5 ).

[0053] A positioning connection block 32 is provided for the two cylindrical guide rods 29 (see Figure 5 ), two cylindrical guide rods 29 are correspondingly inserted into the inner holes of the two sets of coaxial linear bearings 30 (see Figure 5 ), the upper ends of the two cylindrical guide rods 29 are fixedly connected by a positioning connection block 32, and the center distance between the two cylindrical guide rods 29 is maintained (see Figure 5 ), the lower ends of the two cylindrical guide rods 29 are fixedly connected to the W1 axis carriage 4.

[0054] The W1-axis servo drive mechanism is positioned and installed on the Z-axis carriage 2. The W1-axis servo drive mechanism is connected to the W1-axis carriage 4 and can drive the W1-axis carriage 4 to perform digital linear motion in the Z direction between the designed strokes on the Z-axis carriage 2. In this embodiment, the W1-axis servo drive mechanism is composed of a W1-axis lead screw nut pair and a W1-axis servo motor 5. The W1-axis lead screw nut pair is composed of a W1-axis lead screw 33 and a W1-axis nut 34 (see Figure 2 , Figure 5 and Figure 7 ), the W1-axis servo motor 5 is fixedly mounted on the Z-axis carriage 2 via a W1-axis motor base 35 (see Figure 5 ), the motor shaft of the W1-axis servo motor 5 is coaxially fixedly connected with the W1-axis lead screw 33 (see Figure 5 and Figure 7 ), the motor shaft axis of the W1-axis servo motor 5 is parallel to the Z direction (see Figure 7 ), W1 shaft nut 34 cooperates with W1 shaft lead screw 33 (see Figure 5 and Figure 7 ), the W1 shaft nut 34 is fixedly connected with the W1 shaft carriage 4. Figure 5 It can be directly seen that the W1 axis nut 34 is fixedly connected to the positioning connection block 32, the positioning connection block 32 is fixedly connected to the upper ends of the two cylindrical guide rods 29, and the lower ends of the two cylindrical guide rods 29 are fixedly connected to the W1 axis carriage 4. In this embodiment, the W1 axis lead screw nut pair and the W1 axis servo motor 5 use a servo motor with a lead screw nut pair, which has a simpler structure and low cost.

[0055] In the present invention, the guide wire tube 19 is a slender tubular structure (see Figure 1 and Figure 4 ), wherein an axially penetrating wire guide hole is arranged in the middle, the wire guide hole is used to guide automatic wire threading, and the axis of the wire guide hole is parallel to the Z direction. The wire guide tube is a slender tubular structure, which means that the wire guide tube is a tubular structure with a small diameter and a long length, and its diameter is in the range of Φ1-Φ20mm, the length is in the range of 100-1000mm, and the length-to-diameter ratio is in the range of 5:1-500:1. Preferably, the diameter is in the range of Φ2-Φ8mm, the length is in the range of 100-1000mm, and the length-to-diameter ratio is in the range of 10:1-300:1.

[0056] The electrode wire feeding mechanism 20 is positioned and installed on the W1 axis carriage 4 (see Figure 5 ), the wire guide tube 19 is fixedly mounted on the electrode wire feeding mechanism 20 (see Figure 5 ), the electrode wire feeding mechanism 20 is located above the wire guide tube 19 and is arranged directly opposite to the wire insertion opening of the wire guide tube 19 (see Figure 5 ), in the assembled state, the axis of the wire guide tube 19 is parallel to the Z direction (see Figure 5), the electrode wire feeding mechanism 20 is used to digitally feed the electrode wire 21 into or out of the wire guide tube 19. In the present invention, the specific structure of the electrode wire feeding mechanism 20 (also called "wire feeding mechanism") can adopt the existing technology, such as a roller wire feeding mechanism.

[0057] The guide wire tube positioning mechanism 38 is positioned and installed on the Z-axis carriage 2 (see Figure 7 ). The wire guide tube positioning mechanism 38 is used to position the lower part of the wire guide tube 19 (see Figure 5 ), the wire guide tube positioning mechanism 38 is a positioning clamping structure for the lower part of the wire guide tube 19, and a positioning hole (not shown in the figure) is provided on the positioning clamping structure, and the positioning hole is used to position the outer cylindrical surface of the lower part of the wire guide tube 19. The positioning center axis of the positioning hole for the outer cylindrical surface of the lower part of the wire guide tube 19 is coaxial with the axis of the wire guide hole of the wire guide tube 19. The positioning clamping structure can automatically lock or release the lower part of the wire guide tube 19 in the positioning hole under the control of the machine tool control system. In the released state, the W1-axis servo drive mechanism can drive the wire guide tube 19 to move up and down along the axis direction in the positioning hole through the W1-axis carriage 4 (see Figure 5 ).

[0058] The W2 axis motion mechanism includes a W2 axis guide rail 6, a W2 axis first slider 7, a W2 axis second slider 8, a W2 axis first carriage 9, a W2 axis second carriage 10, a tension detector 11, a moving guide wheel 12, a fixed guide wheel 13, a moving guide wheel seat 14, a fixed guide wheel seat 15 and a W2 axis servo drive mechanism (see Figure 8 ),in: The W2 axis guide rail 6 is fixedly mounted on the Z axis carriage seat 1 (see Figure 2 ), the W2 axis first slider 7 and the W2 axis second slider 8 are both installed on the W2 axis guide rail 6 (see Figure 8 ), and the W2-axis first slider 7 and the W2-axis second slider 8 can both move precisely along the W2-axis guide rail 6 in the W2-axis direction (see Figure 8 ), the first slider 7 of the W2 axis is located above the second slider 8 of the W2 axis (see Figure 8 ).

[0059] The W2-axis first carriage 9 is fixedly connected to the W2-axis first slider 7 (see Figure 8 ,exist Figure 2 Because the first slider 7 of the W2 axis is behind the first carriage 9 of the W2 axis and is blocked, the second carriage 10 of the W2 axis is fixedly connected to the second slider 8 of the W2 axis (see Figure 8 ,exist Figure 2 Because the second slider 8 of the W2 axis is behind the second carriage 10 of the W2 axis and is blocked).

[0060] The tension detector 11 has an upper action end 17 and a lower action end 18 (see Figure 8 and Figure 5), the upper action end 17 is fixedly connected to the first carriage 9 of the W2 axis (see Figure 5 ), the lower action end 18 is fixedly connected to the second carriage 10 of the W2 axis (see Figure 8 ), the line connecting the upper action end 17 and the lower action end 18 is parallel to the Z direction, so that the force direction of the tension detector 11 is the Z direction (see Figure 8 ).

[0061] The movable guide wheel 12 is rotatably connected to the movable guide wheel seat 14, and the movable guide wheel 12 is positioned and connected to the second carriage 10 of the W2 axis through the movable guide wheel seat 14 (see Figure 2 ), the axis of the moving guide wheel 12 is perpendicular to the Z direction, the axis of the electrode wire 21 passing by the moving guide wheel 12 and descending in the Z direction is coaxial with the axis of the wire guide hole of the wire guide tube 19 and is parallel to the Z direction (see Figure 2 and Figure 8 The fixed guide wheel 13 is rotatably connected to the fixed guide wheel seat 15, and the fixed guide wheel 13 is fixedly connected relative to the Z-axis carriage seat 1 through the fixed guide wheel seat 15 (see Figure 2 and Figure 8 ), the axis of the fixed guide wheel 13 is parallel to the axis of the movable guide wheel 12.

[0062] The W2-axis servo drive mechanism is positioned and installed on the Z-axis carriage seat 1. The W2-axis servo drive mechanism is connected to the W2-axis first carriage 9 and can drive the W2-axis first carriage 9 and drive the W2-axis second carriage 10 to perform digital linear motion in the Z direction through the tension detector 11. The motion range of the W2-axis first carriage 9 is between the highest position of the W1-axis carriage 4 in the Z direction and the upper limit of the W2-axis first carriage 9. In this embodiment, the W2-axis servo drive mechanism is composed of a W2-axis lead screw nut pair and a W2-axis servo motor 16. The W2-axis lead screw nut pair is composed of a W2-axis lead screw 36 and a W2-axis nut 37 (see Figure 2 ), the motor shaft of the W2-axis servo motor 16 is coaxially fixedly connected with the W2-axis lead screw 36 (see Figure 2 ), the motor shaft axis of the W2-axis servo motor 16 is parallel to the Z direction, the W2-axis nut 37 cooperates with the W2-axis lead screw 36, and the W2-axis nut 37 is fixedly connected to the W2-axis first carriage 9 (see Figure 8 , Figure 8 The middle W2 shaft nut 37 is fixedly connected to the first carriage 9 of the W2 shaft through a transverse rod and a longitudinal rod, but the present invention is not limited to this. Its essence is that the W2 shaft nut 37 is fixedly connected to the first carriage 9 of the W2 shaft).

[0063] In the working state, the electrode wire section that passes by the moving guide wheel 12 and goes down in the Z direction and passes through the wire guide hole of the wire guide tube 19 to the wire guide nozzle on the lower wire arm of the machine tool is the cutting working section of the electrode wire 21 (see Figure 2 and Figure 8 ).

[0064] In the working state, the gravity of the second slider 8 of the W2 axis, the second carriage 10 of the W2 axis, the movable guide wheel seat 14, the movable guide wheel 12, and the tension of the electrode wire 21 acting on the movable guide wheel 12 act vertically downward along the Z direction on the lower acting end 18 of the tension detector 11 (see Figure 8 The W2 axis servo drive mechanism acts vertically upward along the Z direction on the upper action end 17 of the tension detector 11 through the pulling force of the first carriage 9 of the W2 axis (see Figure 8 ), the machine tool control system can realize constant tension control of the electrode wire 21 by servo control of the W2 axis driving the first carriage 9 and the moving guide wheel 12 of the W2 axis according to the tension data of the electrode wire 21 measured by the tension detector 11, and the tension control of the electrode wire 21 directly acts on the cutting working section of the electrode wire 21 (see Figure 8 ). The specific constant tension control process of the electrode wire 21 is: Figure 8As shown, the constant tension control value range of the electrode wire 21 should be set in advance in the machine tool control system. During operation, the machine tool control system detects the current measured tension value through the tension detector 11, and then subtracts the measured tension value from the gravity of the W2 axis second slider 8, the W2 axis second carriage 10, the moving guide wheel seat 14, and the moving guide wheel 12, and then divides it by 2 to obtain the tension of the electrode wire 21 on the cutting working section. Then, the calculated tension of the electrode wire 21 is compared with the set constant tension control value range. When the tension of the electrode wire 21 falls within the constant tension control value range, it remains unchanged. When the tension of the electrode wire 21 is greater than the upper limit of the constant tension control, the machine tool control system starts the W2-axis servo motor 16 to reverse, and the W2-axis nut 37 drives the W2-axis first carriage 9 and the W2-axis first slider 7 to descend. Due to the gravity of the W2-axis second slider 8, the W2-axis second carriage 10, the movable guide wheel seat 14, and the movable guide wheel 12, the W2-axis second slider 8, the W2-axis second carriage 10, the movable guide wheel seat 14, and the movable guide wheel 12 are overall lowered, and the tension of the electrode wire 21 is reduced. The electrode wire 21 is detected, calculated, and compared again until the tension of the electrode wire 21 falls within the constant tension control value range. When the electrode wire 21 is When the tension is less than the lower limit of the constant tension control, the machine tool control system starts the W2 axis servo motor 16 to rotate forward, and the W2 axis nut 37 drives the W2 axis first carriage 9 and the W2 axis first slider 7 to rise, and drives the W2 axis second slider 8, the W2 axis second carriage 10, the moving guide wheel seat 14, and the moving guide wheel 12 to rise as a whole through the upper action end 17, the tension detector 11 and the lower action end 18, and the electrode wire 21 tension increases, and is detected, calculated and compared again until the electrode wire 21 tension falls within the constant tension control value range. It can be seen that by using the W2 axis motion mechanism of the present invention, the machine tool control system can not only realize the constant tension control of the electrode wire 21 by servo control of the W2 axis driving the W2 axis first carriage 9 and the moving guide wheel 12 according to the tension data of the electrode wire 21 measured by the tension detector 11, but also the tension control of the electrode wire 21 directly acts on the cutting working section of the electrode wire 21, so the tension control of the electrode wire in the cutting working section is more direct and more accurate.

[0065] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-axis CNC spindle head for an automatic wire threading CNC electric spark wire cutting machine tool, characterized in that: The three-axis CNC spindle head has a Z-axis motion mechanism, a W1-axis motion mechanism and a W2-axis motion mechanism, and the up and down direction of the machine tool in the working state is defined as the Z direction, wherein the axes of the three axes, the Z-axis, the W1-axis and the W2-axis, are all arranged in parallel in the Z direction; The Z-axis motion mechanism comprises a Z-axis carriage seat (1), a Z-axis carriage (2), a Z-axis guide rail pair, a wire guide tube positioning mechanism (38) and a Z-axis servo drive mechanism, wherein: The Z-axis carriage seat (1) is fixed relative to the machine tool column, and the Z-axis carriage (2) is connected to the Z-axis carriage seat (1) via a Z-axis guide pair, and the Z-axis guide pair guides the Z-axis carriage (2) to perform precise movement in the Z-axis direction; The wire guide tube positioning mechanism (38) is positioned and installed on the Z-axis carriage (2); The Z-axis servo drive mechanism is positioned and mounted on the Z-axis carriage seat (1), the Z-axis servo drive mechanism is drivingly connected to the Z-axis carriage (2), and is capable of driving the Z-axis carriage (2) to perform digital linear motion in the Z direction; The W1-axis motion mechanism comprises a W1-axis carriage (4), a W1-axis guide rail pair, a wire guide tube (19), an electrode wire feeding mechanism (20) and a W1-axis servo drive mechanism, wherein: The W1-axis carriage (4) is connected to the Z-axis carriage (2) via a W1-axis guide pair, and the W1-axis guide pair guides the W1-axis carriage (4) to perform precise movement in the W1-axis direction; The electrode wire feeding mechanism (20) is positioned and mounted on the W1-axis carriage (4); the wire guide tube (19) is fixedly mounted on the electrode wire feeding mechanism (20); in the assembled state, the axis of the wire guide tube (19) is parallel to the Z direction; the electrode wire feeding mechanism (20) is used to digitally feed the electrode wire (21) into or out of the wire guide tube (19); and the wire guide tube positioning mechanism (38) is used to position the lower part of the wire guide tube (19); The W1-axis servo drive mechanism is positioned and mounted on the Z-axis carriage (2), the W1-axis servo drive mechanism is drivingly connected to the W1-axis carriage (4), and is capable of driving the W1-axis carriage (4) to perform digital linear motion in the Z direction between designed strokes on the Z-axis carriage (2); The W2-axis motion mechanism comprises a W2-axis guide rail (6), a W2-axis first slider (7), a W2-axis second slider (8), a W2-axis first carriage (9), a W2-axis second carriage (10), a tension detector (11), a movable guide wheel (12), a fixed guide wheel (13), a movable guide wheel seat (14), a fixed guide wheel seat (15) and a W2-axis servo drive mechanism, wherein: The W2-axis guide rail (6) is fixedly mounted on the Z-axis carriage seat (1); the W2-axis first slider (7) and the W2-axis second slider (8) are both mounted on the W2-axis guide rail (6); and the W2-axis first slider (7) and the W2-axis second slider (8) are both capable of making precise movements along the W2-axis guide rail (6) in the W2-axis direction; the W2-axis first slider (7) is located above the W2-axis second slider (8); The first carriage (9) of the W2 axis is fixedly connected to the first slider (7) of the W2 axis, and the second carriage (10) of the W2 axis is fixedly connected to the second slider (8) of the W2 axis; The tension detector (11) comprises an upper action end (17) and a lower action end (18), the upper action end (17) being fixedly connected to the first carriage (9) of the W2 axis, and the lower action end (18) being fixedly connected to the second carriage (10) of the W2 axis, and the line connecting the upper action end (17) and the lower action end (18) being parallel to the Z direction, so that the force direction of the tension detector (11) is the Z direction; The movable guide wheel (12) is rotatably connected to the movable guide wheel seat (14), and the movable guide wheel (12) is positionally connected to the second carriage (10) of the W2 axis through the movable guide wheel seat (14), the axis of the movable guide wheel (12) is perpendicular to the Z direction, the axis of the electrode wire (21) passing around the movable guide wheel (12) and descending in the Z direction is coaxial with the axis of the wire guide hole of the wire guide tube (19), and is parallel to the Z direction; the fixed guide wheel (13) is rotatably connected to the fixed guide wheel seat (15), and the fixed guide wheel (13) is fixedly connected to the Z-axis carriage seat (1) through the fixed guide wheel seat (15), and the axis of the fixed guide wheel (13) is parallel to the axis of the movable guide wheel (12); The W2-axis servo drive mechanism is positioned and mounted on the Z-axis carriage seat (1), the W2-axis servo drive mechanism is drivingly connected to the W2-axis first carriage (9), and is capable of driving the W2-axis first carriage (9) and, through the tension detector (11), driving the W2-axis second carriage (10) to perform digital linear motion in the Z direction, wherein the motion range of the W2-axis first carriage (9) is between the highest position of the W1-axis carriage (4) in the Z direction and the upper limit position of the W2-axis first carriage (9); In the working state, the electrode wire section that passes around the movable guide wheel (12), descends in the Z direction, passes through the wire guide hole of the wire guide tube (19) to the wire guide nozzle on the lower wire arm of the machine tool is the cutting working section of the electrode wire (21); In the working state, the gravity of the W2-axis second slider (8), the W2-axis second carriage (10), the movable guide wheel seat (14), the movable guide wheel (12), and the tension of the electrode wire (21) acting on the movable guide wheel (12) act vertically downward on the lower action end (18) of the tension detector (11) along the Z direction, and the W2-axis servo drive mechanism acts vertically upward on the upper action end (17) of the tension detector (11) along the Z direction through the pulling force of the W2-axis first carriage (9). The machine tool control system can achieve constant tension control of the electrode wire (21) by servo control of the W2-axis driving the W2-axis first carriage (9) and the movable guide wheel (12) according to the tension data of the electrode wire (21) measured by the tension detector (11), and the tension control of the electrode wire (21) directly acts on the cutting working section of the electrode wire (21).

2. The three-axis CNC spindle head according to claim 1, characterized in that: The wire guide tube (19) is a slender tubular structure, with an axially penetrating wire guide hole arranged in the middle thereof, the wire guide hole being used to guide automatic wire threading, and the axis of the wire guide hole being parallel to the Z direction; The electrode wire feeding mechanism (20) is located above the wire guide tube (19) and is arranged directly opposite to the wire threading entrance of the wire guide tube (19); The wire guide tube positioning mechanism (38) is a positioning clamping structure for the lower part of the wire guide tube (19), and a positioning hole is provided on the positioning clamping structure. The positioning hole is used to position the outer cylindrical surface of the lower part of the wire guide tube (19). The positioning center axis of the positioning hole for the outer cylindrical surface of the lower part of the wire guide tube (19) is coaxial with the axis of the wire guide hole of the wire guide tube (19). The positioning clamping structure can automatically lock or release the lower part of the wire guide tube (19) in the positioning hole under the control of the machine tool control system. In the released state, the W1-axis servo drive mechanism can drive the wire guide tube (19) to move up and down along the axis direction in the positioning hole through the W1-axis drag plate (4).

3. The three-axis CNC spindle head according to claim 1, characterized in that: The Z-axis guide rail pair is composed of a Z-axis guide rail (22) and a Z-axis slider (23). One of the Z-axis guide rail (22) and the Z-axis slider (23) is fixedly mounted on the Z-axis carriage seat (1), and the other is fixedly mounted on the Z-axis carriage (2). The Z-axis guide rail (22) is arranged along the Z-axis. The Z-axis slider (23) is mounted on the Z-axis guide rail (22) and can be precisely moved in the Z-axis direction.

4. The three-axis CNC spindle head according to claim 1, characterized in that: The Z-axis guide rail pair is composed of a Z-axis fixed rail and a Z-axis movable rail. The Z-axis fixed rail is fixedly connected to the Z-axis carriage seat (1), the Z-axis movable rail is fixedly connected to the Z-axis carriage (2), and the Z-axis fixed rail and the Z-axis movable rail are movably matched.

5. The three-axis CNC spindle head according to claim 1, characterized in that: The Z-axis servo drive mechanism is composed of a synchronous pulley pair, a Z-axis lead screw nut pair and a Z-axis servo motor (3), wherein the synchronous pulley pair is composed of a small pulley (24), a large pulley (25) and a synchronous belt (26), and the Z-axis lead screw nut pair is composed of a Z-axis lead screw (27) and a Z-axis nut (28); The Z-axis servo motor (3) is fixedly mounted on the Z-axis carriage seat (1); the Z-axis servo motor (3) is transmission-connected with the small pulley (24); the axis of the Z-axis servo motor (3) is coaxial with the axis of the small pulley (24) and parallel to the Z direction; the small pulley (24) is transmission-connected with the large pulley (25) through a synchronous belt (26); the axis of the small pulley (24) is parallel to the axis of the large pulley (25); the large pulley (25) is transmission-connected with the Z-axis lead screw (27); the Z-axis lead screw (27) cooperates with the Z-axis nut (28); the axis of the large pulley (25), the axis of the Z-axis lead screw (27) and the axis of the Z-axis nut (28) are coaxial with each other and parallel to the Z direction; the Z-axis nut (28) is fixedly connected with the Z-axis carriage (2).

6. The three-axis CNC spindle head according to claim 1, characterized in that: The W1 axis guide pair is composed of a double cylindrical guide rod and a linear guide sleeve combination, wherein the double cylindrical guide rod and linear guide sleeve combination is composed of two cylindrical guide rods (29) and four linear bearings (30); Two bearing seats (31) are provided for the four linear bearings (30), two linear bearings (30) are fixedly mounted in parallel on one bearing seat (31), and the other two linear bearings (30) are fixedly mounted in parallel on the other bearing seat (31), the two bearing seats (31) are arranged at a distance in the upper and lower directions in the Z direction, and are fixedly mounted on the Z-axis carriage (2), the axes of the four linear bearings (30) on the two bearing seats (31) are coaxial in pairs in the upper and lower directions, and are parallel in pairs in the left and right directions and are parallel to the Z direction, thereby forming two groups of coaxial linear bearings (30); A positioning connection block (32) is provided for the two cylindrical guide rods (29). The two cylindrical guide rods (29) are correspondingly inserted into the inner holes of the two sets of coaxial linear bearings (30). The upper ends of the two cylindrical guide rods (29) are fixedly connected by the positioning connection block (32) and the center distance between the two cylindrical guide rods (29) is maintained. The lower ends of the two cylindrical guide rods (29) are fixedly connected to the W1 axis carriage (4) in a positioning manner.

7. The three-axis CNC spindle head according to claim 1, characterized in that: The W1-axis servo drive mechanism is composed of a W1-axis lead screw nut pair and a W1-axis servo motor (5) connected together; the W1-axis lead screw nut pair is composed of a W1-axis lead screw (33) and a W1-axis nut (34); the W1-axis servo motor (5) is fixedly mounted on the Z-axis carriage (2) via a W1-axis motor seat (35); the motor shaft of the W1-axis servo motor (5) is coaxially fixedly connected to the W1-axis lead screw (33); the motor shaft axis of the W1-axis servo motor (5) is parallel to the Z direction; the W1-axis nut (34) cooperates with the W1-axis lead screw (33); and the W1-axis nut (34) is fixedly connected relative to the W1-axis carriage (4).

8. The three-axis CNC spindle head according to claim 7, characterized in that: The W1-axis lead screw nut pair and the W1-axis servo motor (5) are servo motors with built-in lead screw nut pairs.

9. The three-axis CNC spindle head according to claim 1, characterized in that: The W2-axis servo drive mechanism is composed of a W2-axis lead screw nut pair and a W2-axis servo motor (16) connected together; the W2-axis lead screw nut pair is composed of a W2-axis lead screw (36) and a W2-axis nut (37); the motor shaft of the W2-axis servo motor (16) is coaxially fixedly connected to the W2-axis lead screw (36); the motor shaft axis of the W2-axis servo motor (16) is parallel to the Z direction; the W2-axis nut (37) cooperates with the W2-axis lead screw (36); and the W2-axis nut (37) is fixedly connected to the W2-axis first carriage (9).

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